With the rapid development of communication technologies, network banking has provided people with more and more efficient and convenient services. In daily life, people can connect to a network banking server through Point Of Sale (POS) devices provided by sellers, thereby implementing fast and convenient network banking services. Two types of common POS devices exist, which are wired connection and wireless connection. During the implementation of the present invention, the inventors find that the conventional art has at least the following disadvantages and deficiencies. The wired connection is to connect a POS device to a private network for network banking through physical lines, the connection mode greatly restricts the application occasion and range of the POS device, and the cost of manufacturing, deploying, and maintaining the POS device is high; while the wireless connection is to connect a POS device to a banking server through a private wireless network for network banking so as to implement network banking services, the POS device of wireless connection requires not only the function of banking services but also the function of wireless communication, so that the functions of the POS device are complicated, and the cost for manufacturing and maintenance is even higher.